Display screen or portion thereof with a graphical user interface



The FIGURE is a front view of a display screen or portion thereof with agraphical user interface showing our new design.

The dot dashed broken line showing the display screen or portion thereofforms no part of the claimed design. The dashed broken line showingportions of the graphical user interface forms no part of the claimeddesign.

CLAIM The ornamental design for a display screen or portion thereof witha graphical user interface, as shown and described.